Pneumothorax and air travel in adults

INTRODUCTION — 

It is estimated that over one billion passengers travel by air each year [1-3]. Although up to 5 percent of passengers have some form of disability or chronic medical illness, in-flight emergencies are infrequent [4]. Only one of every 39,000 passengers (0.003 percent) experiences an in-flight emergency [5,6]. Death during commercial flight is even more rare [7-9].

This topic reviews the incidence, pathogenesis, and management of in-flight pneumothorax and assessment of adult patients for the risk of in-flight pneumothorax before air travel.

General preflight medical assessment, the prevention of in-flight hypoxemia, the management of other medical events, and the management of spontaneous pneumothorax are discussed separately.

●(See "Assessment of adult patients for air travel".)

●(See "Evaluation of patients for supplemental oxygen during air travel".)

●(See "Treatment of secondary spontaneous pneumothorax in adults".)

●(See "Treatment of primary spontaneous pneumothorax in adults".)

●(See "Pneumothorax: Definitive management and prevention of recurrence".)

●(See "Management of inflight medical events on commercial airlines".)

Guidelines regarding pneumothorax and air travel are based upon limited data [7,10,11]. We adhere to these guidelines for the most part and deviate when our opinion differs.

PATHOGENESIS — 

The majority of in-flight pneumothoraces are thought to be due to rupture of a cyst, bulla, or bleb. Rupture is likely due to gas expansion from subatmospheric cabin pressure during the flight.

Boyle's law states that the volume of a gas is inversely proportional to the pressure to which it is exposed. As altitude increases, barometric (atmospheric) pressure decreases. Thus, as barometric pressure falls in the aircraft cabin during the ascent, trapped air in any noncommunicating body cavity (eg, lung bleb, lung bulla, lung cyst, paranasal sinuses) will expand and potentially rupture [12-16]. Further air expansion can result in tension pneumothorax that is life-threatening [13,15,16]. Even without rupture, the expansion of trapped air can potentially cause compression of functional lung, mediastinal shift, and circulatory compromise.

Other mechanisms may play a role including the following:

●Air trapping – For patients with underlying obstructive lung disease, trapped air due to airflow obstruction (eg, during a chronic obstructive pulmonary disease exacerbation) [17,18] may also contribute to gas expansion during flight at cabin altitude. (See 'Others' below.)

●High moisture – Expansion of gas in the lungs is also increased by high moisture content because of higher vapor pressure which lowers the gas pressure [12,19].

●Gravitational forces (g-forces) – High g-forces do not occur during commercial air travel but are important considerations for military aviators and test pilots who fly high-performance aircraft. Very low intrapleural pressures (-32 cm H₂O) over the apical surfaces of the lung have been noted at high g-forces [15]. Pneumothorax, pneumomediastinum, and hemoptysis can result from these disruptive forces [15,20,21].

Regulatory agencies, such as the Federal Aviation Administration (FAA), require commercial aircraft cabins to be pressurized to simulate an altitude below 8000 feet (2438 meters). In case of any probable failure in the pressurization system, by law, aircraft are designed in a way that the occupants should not be exposed to cabin pressure attitudes in excess of 15,000 feet [22]. Most aircraft allow only brief diversions to a cabin altitude of 10,000 feet (3048 meters) for safety (eg, to avoid adverse weather). Different types of aircraft can achieve different degrees of pressurization, but most aircraft can be pressurized to 400 or 450 mmHg above the actual atmospheric pressure outside the aircraft (table 1) [23]. Thus, for most commercial airlines, cabin pressure is generally lower than atmospheric pressure at high altitude, which results in gas expansion inside the lungs, increasing the risk of cyst or bleb rupture to precipitate pneumothorax (table 2) [23]. It is estimated that the volume of air in a noncommunicating body cavity will increase by approximately 38 percent upon ascent from sea level to the maximum "cabin altitude" of 8000 feet (2438 meters) [10,13].

INCIDENCE — 

The overall incidence of in-flight pneumothorax appears to be low. However, data are limited to isolated case reports, which are mostly derived from at-risk populations, in whom the baseline risk is often also poorly quantified. At-risk populations are discussed below. (See 'At-risk populations' below.)

In the general population, the exact incidence of pneumothorax during commercial air travel is unknown due to nonstandardized reporting requirements for in-flight medical emergencies, diagnostic uncertainty during flight, and possible delay in symptoms (ie, pneumothorax may develop within 24 hours or more after the flight) [24]. However, in-flight pneumothorax is likely rare since it is not mentioned in most reports addressing in-flight emergencies [5,6,25-30].

As an example, between 1986 and 1988, the Federal Aviation Administration (FAA) reported a total of 2322 emergencies. Only one definite and one possible pneumothorax were reported, although case descriptions were limited and the diagnoses were not necessarily confirmed medically [30]. In comparison, the reported incidence of spontaneous pneumothorax not associated with air travel in the general population ranges from 7 to 18 per 100,000/year for males and 1 to 6 per 100,000/year for females [31,32].

COUNSELING AT-RISK PATIENTS REGARDING AIR TRAVEL — 

Patients with underlying risk factors (see 'At-risk populations' below) who plan to travel by air often need an assessment in advance of the flight. Assessing the risk of pneumothorax during flight is dependent upon whether the patient has a pneumothorax or not (see 'No current pneumothorax' below and 'Current pneumothorax' below) as well as several additional factors, which are discussed in the sections below. (See 'Factors involved in the assessment' below.)

General preflight assessment is discussed separately. (See "Assessment of adult patients for air travel" and "Evaluation of patients for supplemental oxygen during air travel" and "Approach to patients with heart disease who wish to travel by air or to high altitude".)

At-risk populations — Based upon limited data and our experience, we consider patients with underlying cystic or interstitial lung disease (ILD), patients with recent surgical or nonsurgical trauma to the chest, and military aviators to be at risk of in-flight pneumothorax. However, pneumothorax has been reported in patients without lung diseases [8]. Thus, not having underlying lung disease does not eliminate the risk.

Cystic lung disease — Patients with any cystic lung disease (table 3) are at risk of spontaneous pneumothorax during flight. While patients with pulmonary lymphangioleiomyomatosis (LAM) are at highest risk, patients with bullous lung disease due to chronic obstructive pulmonary disease (COPD) are seen more commonly due to the higher prevalence of COPD.

●LAM – The risk of in-flight pneumothorax in patients with LAM is discussed separately. (See "Sporadic lymphangioleiomyomatosis: Treatment and prognosis", section on 'Air travel'.)

●Bullous emphysema – Data are insufficient to calculate the exact risk of in-flight pneumothorax for patients with bullous emphysema [9]. The large number of travelers with COPD combined with the low overall rate of pneumothorax suggest that the absolute risk of in-flight pneumothorax is low in COPD, perhaps higher if they have other risk factors (eg, recent surgery, biopsy, previous pneumothorax). Importantly, the impact of pneumothorax is potentially life-threatening in this population if there is underlying cardiovascular disease and/or respiratory failure (the latter is more common than pneumothorax during flight). (See "Treatment of secondary spontaneous pneumothorax in adults".)

●Intrapulmonary bronchogenic or other congenital cyst – Though rare, intrapulmonary bronchogenic cysts have been associated with pneumothorax during ascent to high altitude by aircraft or train, sometimes in association with cerebral air embolism [33,34]. (See 'Other barotrauma during air travel' below.)

The incidence among patients with congenital intrapulmonary lung cysts is not known. (See "Congenital anomalies of the intrathoracic airways and tracheoesophageal fistula", section on 'Bronchogenic cyst'.)

●Birt-Hogg-Dubé (BHD) syndrome – While patients with BHD are at increased risk of spontaneous pneumothorax at sea level, one retrospective analysis reported that among 40 patients with BHD who traveled by air for over 2000 flights, none developed a pneumothorax [35]. In contrast, a questionnaire-based study reported a risk of 0.63 percent per flight and that 9 percent developed pneumothorax within one month of traveling by air [36]. Another survey reported that 8 out of 104 patients developed a pneumothorax during or within 24 hours following a flight [37]; the estimated risk was approximately 0.12 percent per flight. (See "Birt-Hogg-Dubé syndrome", section on 'Pulmonary manifestations'.)

●Pulmonary Langerhans cell histiocytosis (PLCH) – Patients with PLCH are at increased risk of spontaneous pneumothorax. One patient survey reported that air travel-related pneumothorax in this population was approximately 2.4 percent per patient and 0.27 percent per flight [38]. (See "Pulmonary Langerhans cell histiocytosis".)

Other etiologies of cystic lung diseases are listed in the table (table 3), all of which may predispose a patient to in-flight pneumothorax. The evaluation of patients with cystic lung disease and the epidemiology and etiology of secondary pneumothorax are provided in separate topic reviews. (See "Diagnostic approach to the adult with cystic lung disease" and "Pneumothorax in adults: Epidemiology and etiology".)

Interstitial lung disease — While any ILD can be associated with in-flight pneumothorax, idiopathic pulmonary fibrosis (IPF) and sarcoidosis are more commonly encountered.

Limited data suggest either no or minimal increased risk during air travel. As an example, one study that examined the risk of in-flight pneumothorax by chest computed tomography (CT) in 76 patients with IPF after 159 trips by air showed that no patient developed a pneumothorax [39]. Similarly, among 92 patients with sarcoidosis who had chest CT scans after a total of 121 trips by air, none developed a pneumothorax [39].

Lung biopsy — Few studies describe the risk of air travel in patients who undergo lung needle biopsy. One study reported that among those who developed a pneumothorax following transthoracic needle biopsy (TTNB), including patients with radiographic evidence of residual pneumothorax, three-quarters had traveled by air within four days of the final postbiopsy chest radiograph [40]. Approximately, 8 percent developed symptoms during or shortly after flying. Although unclear, patients undergoing TTNB may be a greater risk compared with transbronchial biopsy (TBB) since TTNB compromises the pleural membranes.

Trauma/thoracic surgery — Chest trauma, particularly thoracic or cardiac surgery, places patients at risk for pneumothorax. However, no robust data have estimated the risk of pneumothorax associated with flying. In a survey of 68 thoracic surgeons who were asked about the optimal time for air travel following surgery, only one surgeon recalled one adverse in-flight event in a patient who developed thoracic pain during ascent of the aircraft [41]. Case reports following chest trauma have also been described [42].

Military jet aviation — Several case reports describe pneumothorax in military aviators, which is thought to be due to repeated use of Valsalva maneuvers during flight [43-45].

No current pneumothorax

General advice — For patients without an acute pneumothorax or recent trauma or surgery, we provide reassurance that the risk of pneumothorax during air travel is generally low (eg, <1 percent per flight). We also inform patients that the individual risk is unknown (due to limited data) and varies with the underlying disorder, that treatment in-flight is limited, and that pneumothorax can be life-threatening if tension occurs.

Because the range of risk is wide, we individualize the decision to fly. As examples:

●On one end of the spectrum, we would permit air travel in a patient with mild cystic lung disease who has no previous pneumothorax, has good cardiopulmonary function, and is taking a short domestic flight (eg, one to three hours). On the other end, we would advise against air travel for a patient with severe bullous emphysema, recurrent pneumothorax, significant cardiorespiratory comorbidities, and plans to take a transoceanic flight. Domestic flight and transoceanic flights differ in the altitude at which they operate (eg, transoceanic flights often fly at an altitude of >30,000 feet). (See 'Factors involved in the assessment' below.)

●If a patient with underlying lung disease experiences an increase in dyspnea or onset of chest pain in the days to weeks prior to air travel, we typically obtain a preflight chest radiograph or CT scan since a pneumothorax would preclude travel. Sometimes we obtain chest imaging within six months of a prior pneumothorax to ensure complete resolution. (See 'Acute or chronic pneumothorax' below.)

●For patients with an exacerbation of their underlying lung disease (eg, COPD, bullous emphysema, LAM, ILD), we advise postponing air travel until the exacerbation has fully resolved. The rationale for this is based upon the theoretical risk that air trapping due to the exacerbation may worsen gas expansion that occurs during flight and precipitate a pneumothorax. (See 'Pathogenesis' above.)

Factors involved in the assessment — The decision to permit air travel in at-risk patients is highly individualized, and consulting a pulmonologist is appropriate. We generally take into account the following factors:

●Presence of pneumothorax. (See 'Current pneumothorax' below.)

●Previous history of pneumothorax and treatment for it. (See 'Previous history of pneumothorax, timing, and treatment type' below.)

●The type and severity of underlying lung disease. (See 'Type and severity of underlying lung disease' below.)

●Comorbidities, duration of the flight, and patient preferences. (See 'Others' below.)

Previous history of pneumothorax, timing, and treatment type — Patients with a history of pneumothorax are at increased risk of developing pneumothorax in-flight, especially those who have had multiple recurrences (eg, LAM). However, no studies have quantified this risk. While those with recent pneumothorax (eg, within 14 days) are at highest risk and should not travel by air, those with a more distant history are at lower risk (although it is unclear when risk returns to baseline). Further details are below. (See 'Current pneumothorax' below.)

The impact of pneumothorax-directed therapy received in the past on the risk of in-flight pneumothorax is unclear. However, it is reasonable to assume that in patients who were treated with pleurodesis, the risk of in-flight pneumothorax on the treated side is likely lower than baseline, but not zero. Limited data in patients with BHD support this lower risk; among eight patients who developed 11 pneumothoraces related to air travel, only one had previous pleurodesis [37]. However, despite pleurodesis, the patient is still at risk of pneumothorax, particularly on the contralateral (untreated) side.

The impact of previous therapies other than pleurodesis (eg, chest tube, blebectomy) is unknown. (See "Treatment of secondary spontaneous pneumothorax in adults" and "Pneumothorax: Definitive management and prevention of recurrence".)

Type and severity of underlying lung disease — While unproven, patients with severe bullous or cystic lung disease may be more likely to develop air travel-related pneumothorax than patients with mild or minimal lung disease. Patients with severe disease may also be at greater risk of developing cardiopulmonary compromise if tension develops. [13,46].

Others — Other factors involved in making the decision include the following:

●Comorbidities (eg, cardiopulmonary disorders, exacerbations) – Patients with coexisting cardiopulmonary disorders are at greater risk of developing cardiopulmonary compromise as a consequence of pneumothorax, which often discourages clinicians from permitting air travel. However, no data support or have quantified the risk. Risk of air travel in those with cardiovascular disorders is discussed in a separate topic review. (See "Approach to patients with heart disease who wish to travel by air or to high altitude".)

Patients with an exacerbation of their underlying lung disease (eg, COPD, asthma, bullous emphysema, LAM, ILD) may also be at increased risk of developing an in-flight pneumothorax due to air trapping associated with an exacerbation. (See 'Pathogenesis' above.)

●Duration and route (eg, transoceanic) of air travel – While no data have shown an increased risk of pneumothorax with prolonged travel duration, transoceanic flights may pose a greater challenge since they fly at higher altitudes and diverting the aircraft to a nearby airport may be less feasible should a chest tube/catheter need to be placed.

●Patient preferences – Some patients are risk-averse and choose an alternate mode of transport while others are reassured by the low rate and make an informed decision about traveling by air based upon all the factors included in their evaluation.

Current pneumothorax

Acute or chronic pneumothorax — The risk of air travel differs depending on whether the pneumothorax is acute or chronic.

●Acute pneumothorax – For patients with an acute pneumothorax, air travel is contraindicated. We advise not traveling until complete resolution of a pneumothorax has been radiographically documented. This recommendation is based upon the rationale that pneumothorax will potentially worsen in flight and could precipitate tension pneumothorax. (See 'Pathogenesis' above.)

The risk in patients with small stable pneumothoraces or patients who have a functioning chest tube in place is unclear:

•Small stable pneumothorax – While we generally do not permit travel in those with a small stable pneumothorax, data suggest that the risk of worsening the pneumothorax is low.

-In an observational study of 50 patients with a small pneumothorax following TTNB, air travel within four days of a chest radiograph showing a residual pneumothorax was not associated with any need for in-flight medical attention [40]. Less than 8 percent experienced minor chest symptoms during air travel.

-In another retrospective study of patients with traumatic pneumothorax, 10 patients who flew with a small stable pneumothorax and five patients with an isolated pneumothorax on CT had no complications during or following the flight [47].

Further study is needed to evaluate the safety of short-duration air travel for patients with small, stable pneumothoraces, but without other underlying lung disease.

•Chest tube in place – Generally, we do not permit travel with a chest tube (including a tunneled pleural catheter) in place unless the patient has a medical indication (eg, needs transfer to a tertiary care facility for a life-threatening condition) and/or is under medical supervision by skilled staff with supplies to place an additional chest tube/catheter if needed. Data are limited. One case report described an uneventful flight of a patient with a pneumothorax who had a chest tube in place with a unidirectional flutter valve (Heimlich valve) attached [48]. However, worsening pneumothorax remains a possibility. For example, emergent air travel of patients with pneumothoraces has been reported during war time [49]. Two of three such patients who were transported at >9000 feet in an unpressurized cabin tolerated the trip; one died of bilateral pneumothoraces.

●Chronic loculated pneumothorax—Unlike acute pneumothorax, chronic loculated pneumothorax is not an absolute contraindication to air travel. In this population, we assess the duration of chronicity and the patient's air travel history and individualize our recommendation depending on other factors involved. (See 'Factors involved in the assessment' above.)

The risk of pneumothorax in patients with chronic loculated pneumothorax appears to be lower than that with acute pneumothorax. Biologically, chronic loculated lung is likely adherent to the chest wall due to previous inflammation and fibrosis, thereby preventing collapse. In addition, limited data support a lower risk in this population compared with acute pneumothorax [39,50]. For example, in a study of 281 patients with LAM, 8 patients who had chronic pneumothorax traveled by airline without incident. The average chronicity of the pneumothoraces was approximately two years (range of one to four), and two patients had prior pleurodesis. There was no progression in pneumothorax volume over the four-year study period.

Timing air travel after resolution or surgery — The optimal length of time to wait after resolution of a pneumothorax before traveling by air is not known [51]. However, we individualize the decision by taking into consideration all the relevant factors that are important for the decision. (See 'Factors involved in the assessment' above.)

The following principles may be helpful:

●Guidelines regarding timing are variable but generally suggest that one to three weeks is a reasonable period to wait following resolution. While the Aerospace Medical Association suggests delaying air travel for two to three weeks following resolution of pneumothorax or after uncomplicated thoracic surgery [7], the British Thoracic Society guidelines recommends a delay of one week after radiographic resolution of spontaneous pneumothorax and preferably a two-week delay for traumatic pneumothorax [11].

●Our approach is similar for those with an iatrogenic pneumothorax and relatively normal lung parenchyma, in whom we generally permit air travel two weeks after radiographic resolution. In contrast, we may prohibit air travel for ≥12 months in patients with recurrent spontaneous pneumothorax who have severe bullous emphysema and limited cardiopulmonary reserve.

●Most clinicians advise waiting three to four weeks after resolution of any postsurgical pneumothorax occurring in association with major surgery (cardiac or thoracic surgery).

●For patients who are stable after a mediastinoscopy who have no underlying lung disease, delaying air travel is usually not necessary.

●For patients who have had a minor lung biopsy (eg, TTNB, TBB), we propose waiting for two weeks before permitting air travel.

Data on the optimal timing of air travel following an acute pneumothorax are limited and derived from heterogeneous populations.

●Traumatic pneumothorax – In one prospective study, among 12 patients with a recent nonsurgical traumatic pneumothorax, patients who waited for at least 14 days after radiographic resolution of the pneumothorax and were asymptomatic in-flight did not have a recurrence while one of two patients who flew sooner than 14 days developed respiratory distress suggestive of a recurrence [52]. In contrast, a retrospective series of patients with nonsurgical traumatic pneumothorax reported that, of the 58 patients who flew within nine days of chest tube removal, none had a complication [47].

●Thoracic/cardiac surgery – In a survey of 68 thoracic surgeons, 44 percent allowed their patients to fly after a variable length of time (up to 42 days) after complete radiographic resolution of a postoperative pneumothorax [41]. Seventy-seven percent allowed their patients to fly without delay following mediastinoscopy, even with a residual pneumomediastinum. In this survey, the only adverse in-flight event reported was a case of thoracic pain during ascent of the aircraft.

EVALUATION AND MANAGEMENT IN-FLIGHT PNEUMOTHORAX — 

This section provides information on the diagnostic and management strategies needed for patients who develop suspected pneumothorax during air travel.

Diagnostic evaluation — During air travel, the clinician is reliant upon clinical findings to make the diagnosis since confirmatory imaging, the diagnostic gold standard, is not usually feasible. Some airlines may have limited supplies for examination, such as a stethoscope, pressure manometer, and a peripheral oximeter. However, the quality of this equipment is not assured and surrounding ambient noise may interfere with the examination.

●Suspecting pneumothorax – In-flight pneumothorax should be suspected in a patient with risk factors (see 'At-risk populations' above) who develops chest pain and/or dyspnea. However, the risk factor is not always clear at the time of presentation. We enquire about any past medical or family history of lung disorders; pneumothorax; or recent procedures, surgery, or trauma. If the patient has had a previous pneumothorax, we ask whether the nature of the symptoms is similar, what was the situation under which it occurred, and how it was treated.

●Clinical manifestations – The clinical manifestations of pneumothorax arising at high altitude are the same as those at sea level. This includes chest pain (sometimes pleuritic) and dyspnea; when large, pneumothorax is associated with tachypnea and tachycardia, decreased chest excursion, diminished breath sounds, hyperresonant percussion on the affected side, and (rarely) subcutaneous emphysema (which usually indicates pneumomediastinum or pneumothorax in conjunction with pneumomediastinum) [25-27,53]. Tension pneumothorax may additionally present with tracheal deviation and hypotension. Further details on the clinical presentation and diagnostic evaluation of pneumothorax are provided separately. (See "Clinical presentation and diagnosis of pneumothorax", section on 'Clinical manifestations'.)

●Differential and diagnosis – The differential diagnosis is also similar to that at sea level. Among the potential disorders, competing life-threating diagnoses include an acute exacerbation of their underlying lung disease, acute ischemic cardiovascular disease, acute heart failure, and pulmonary embolism (PE). Differentiating these entities in a hospital setting is discussed separately. (See "Clinical presentation and diagnostic evaluation of the nonpregnant adult with suspected acute pulmonary embolism", section on 'Differential diagnosis'.)

Since all of these etiologies generally require imaging, electrocardiography, and laboratory testing (none of which are typically available in-flight), the clinician should rely on clinical manifestations to differentiate these important etiologies:

•The quality of the pain – Pleuritic pain would support both PE and pneumothorax while crushing pain may support cardiac disease, anterior wall tenderness would support musculoskeletal etiology, and heartburn would support gastroesophageal reflux disease. (See "Approach to the adult with nontraumatic chest pain in the emergency department".)

•Breath sounds – Diminished breath sounds or no air entry would support a pneumothorax while wheeze might support an exacerbation, crackles might support heart failure (or interstitial lung disease), and clear air entry might support PE (or a small pneumothorax).

•Tracheal position – A deviated trachea may support a pneumothorax especially in conjunction with other features. However, it could also be associated with severe unilateral fibrosis. A centrally positioned trachea does not rule out pneumothorax.

•Subcutaneous air – Palpating subcutaneous air is a strong indication of barotrauma including pneumothorax and/or pneumomediastinum, but cannot distinguish between these two entities.

●Diagnosis – Ultimately the clinician may make an empiric clinical diagnosis based upon a culmination of findings. For example, a young patient with a history of recent chest trauma who is in respiratory distress and has a deviated trachea, hyperresonance on percussion, reduced air entry on auscultation, and subcutaneous air has a high possibility of having a pneumothorax. In contrast, a patient with minor nonpleuritic chest pain who has no other findings is less likely to have a pneumothorax or at least to have significant pneumothorax. Assessment with imaging postflight is essential to confirm the diagnosis. (See 'Postflight management' below.)

In-flight management — For patients who develop symptoms and signs of a pneumothorax in flight, we administer supplemental oxygen, which is usually readily available during commercial flights. In addition, pain control with over-the-counter analgesics is also appropriate, if indicated and available.

Additional management decisions, such as aspiration or the need for chest catheter/tube insertion and flight diversion to the nearest airport, should be addressed. We individualize this decision, which depends upon the clinical status of the patient, available medical supplies, and the route of air travel. As examples:

●Patients who are mildly symptomatic and close to their destination may not need a catheter or aspiration before landing.

●In contrast, those with significant symptoms or oxygen desaturation may need urgent medical attention, which requires descent to the nearest airport for landing and disembarkation for medical attention.

●For patients with respiratory distress and/or hemodynamic instability, especially those in whom tension is suspected, urgent decompression (and drainage, if feasible) will need to be undertaken using available supplies but is dependent upon a clinician with expertise on board. Emergency medical kits vary from airline to airline but usually include needles, intravenous catheters, gloves, and syringes. A makeshift chest tube has been described using a scalpel, coat hanger, urinary catheter, oxygen tubing, and a bottle of water for underwater seal drain [42]. Emergency methods for chest decompression and the technique of chest tube insertion are discussed in detail separately. (See "Initial evaluation and management of penetrating thoracic trauma in adults", section on 'Role of needle/finger chest decompression' and "Thoracostomy tubes and catheters: Placement techniques and complications".)

Postflight management — We advise medical evaluation following disembarkation and, if pneumothorax is confirmed but the underlying risk factor is not evident, an assessment should be undertaken to explain in-flight pneumothorax (table 4). This evaluation is discussed separately. (See "Clinical presentation and diagnosis of pneumothorax", section on 'Diagnostic imaging' and "Clinical presentation and diagnosis of pneumothorax", section on 'Postdiagnosis evaluation'.)

OTHER BAROTRAUMA DURING AIR TRAVEL — 

Other forms of pulmonary barotrauma can occur during air travel. These include pneumomediastinum, systemic air embolism, and bulla expansion with hemorrhage. Limited descriptions regarding their risk, presentation, and management exist. Presumably, they are rare and the pathogenetic mechanism may be similar to that described for pneumothorax. (See 'Pathogenesis' above.)

●Pneumomediastinum – Pneumomediastinum during air travel has been described in a few case reports and may or may not coexist with pneumothorax [34,54,55]. Reported precipitating factors have included upper respiratory tract infection, multiple Valsalva maneuvers in-flight, and rupture of a bronchogenic cyst. At least one event without an apparent risk factor has been described [55].

Symptoms and signs of a pneumomediastinum include chest pain (typically retrosternal), throat pain, and dyspnea [56,57]. The key finding on physical examination is subcutaneous emphysema, usually over the neck and shoulders.

Most patients are managed supportively with oxygen using the same principles as described for in-flight pneumothorax. However, a chest tube/catheter will not treat pneumomediastinum unless coexistent pneumothorax is present. Thoracotomy for tension pneumomediastinum is not usually feasible in commercial airlines. (See 'Evaluation and management in-flight pneumothorax' above and 'Counseling at-risk patients regarding air travel' above and "Diagnosis, management, and prevention of pulmonary barotrauma during invasive mechanical ventilation in adults", section on 'Pneumomediastinum'.)

●Systemic air embolism – Case reports of systemic air embolism have also been described, some of which were fatal (eg, due to cerebral embolization) or associated with neurologic illness [33,53,58,59]. The presentation and management of suspected air embolism are provided in a separate topic review. (See "Air embolism".)

●Cyst hemorrhage – One case of a patient with bullous emphysema who likely developed an in-flight cyst hemorrhage has been described [60]. The patient complained of recurrent hemoptysis during two consecutive flights, which was managed conservatively. Subsequent imaging after landing revealed a new fluid-air level within the bulla, which was resected. On pathologic examination, a thick fibrous wall showed hemorrhage.

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Pneumothorax" and "Society guideline links: Management of inflight medical events".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Pneumothorax (collapsed lung) (The Basics)")

PATIENT PERSPECTIVE TOPIC — 

Patient perspectives are provided for selected disorders to help clinicians better understand the patient experience and patient concerns. These narratives may offer insights into patient values and preferences not included in other UpToDate topics. (See "Patient perspective: Lymphangioleiomyomatosis (LAM)".)

SUMMARY AND RECOMMENDATIONS

●Epidemiology and pathogenesis – Pneumothorax during air travel is infrequent. The majority are due to cyst/bleb/bulla rupture from gas expansion, which in turn is due to reduced cabin pressure during the flight. Most patients have a risk factor including underlying cystic or interstitial lung disease, recent surgical or nonsurgical trauma to the chest, or military aviation. (See 'Pathogenesis' above and 'Incidence' above.)

●Counseling on risk before travel – The decision to permit air travel in at-risk patients is individualized, and consulting a pulmonologist is appropriate. (See 'At-risk populations' above.)

Assessing the risk of pneumothorax in advance of air travel is dependent upon several factors including the following:

•Presence of acute pneumothorax. (See 'Current pneumothorax' above and 'No current pneumothorax' above.)

•Previous history of and treatments for pneumothorax. (See 'Previous history of pneumothorax, timing, and treatment type' above.)

•Type and severity of underlying lung disease. (See 'Type and severity of underlying lung disease' above.)

•Other factors including comorbidities, duration and route of air travel, and patient preferences. (See 'Others' above.)

●No current pneumothorax – For patients without a pneumothorax or recent trauma or surgery, we provide reassurance that the risk of air travel is generally low (eg, <1 percent), provided no additional worrisome features are present (eg, previous pneumothorax, severe underlying lung disease, or large bulla). However, the range of risk is wide, based upon limited data, and varies from patient to patient. Thus, the decision to permit air travel is individualized. As examples:

•On one end of the spectrum, we would permit air travel in a patient with mild cystic lung disease who has no previous pneumothorax, has good cardiopulmonary function, and is taking a short domestic flight (eg, one to three hours). On the other end, we would advise against air travel for a patient with severe bullous emphysema, with recurrent pneumothorax, with significant cardiorespiratory comorbidities, and planning to take a transoceanic flight. (See 'No current pneumothorax' above.)

•If a patient with underlying lung disease experiences an increase in dyspnea or onset of chest pain in the days to weeks prior to air travel, we typically obtain a preflight chest radiograph or CT scan since a pneumothorax would preclude travel.

•For patients with an exacerbation of their underlying lung disease, we advise postponing air travel until the exacerbation has fully resolved. Air trapping due to the exacerbation may worsen gas expansion that occurs during flight and precipitate a pneumothorax.

●Current pneumothorax – Management depends upon whether the pneumothorax is acute or chronic. (See 'Current pneumothorax' above and 'Acute or chronic pneumothorax' above.)

•Acute pneumothorax – In most patients with an acute pneumothorax, air travel is contraindicated until complete resolution of the pneumothorax has been radiographically documented. Pneumothorax worsens in flight and could progress to tension pneumothorax, which is life-threatening. The risk in patients with small, stable pneumothoraces or patients who have a functioning chest tube in place is unclear.

The optimal length of time to wait after resolution of an acute pneumothorax before traveling by air is not known. We feel the decision about air travel must be made on an individual basis. (See 'Current pneumothorax' above and 'Timing air travel after resolution or surgery' above.)

•Chronic loculated pneumothorax – We do not consider chronic loculated pneumothorax a contraindication to air travel based upon limited data that suggest many patients in this category have undertaken air travel uneventfully.

●Evaluation and management in-flight pneumothorax

•Diagnostic evaluation – In-flight pneumothorax should be suspected in a patient with risk factors who develops the typical symptoms and signs of a pneumothorax, like those experienced at sea level (eg, chest pain and dyspnea). However, during flight, the clinician is reliant upon clinical findings to make the diagnosis since confirmatory imaging is not feasible. The clinical diagnosis is also challenging given the ambient noise and limited diagnostic tools. (See 'Diagnostic evaluation' above and "Clinical presentation and diagnosis of pneumothorax".)

•In-flight management – For patients who develop symptoms and signs of a pneumothorax during flight, we administer supplemental oxygen and (if indicated and available) over-the-counter analgesia. (See 'In-flight management' above.)

We individualize the decision for chest catheter/tube insertion.

-For patients with significant symptoms, emergency landing at the nearest airport will allow prompt evaluation and insertion of a chest tube, if needed. (See "Treatment of primary spontaneous pneumothorax in adults", section on 'Catheter or chest tube thoracostomy'.)

-For those with respiratory distress and/or hemodynamic instability, especially those in whom tension is suspected, urgent decompression may be needed, if the expertise is available. These details may be provided separately. (See "Initial evaluation and management of penetrating thoracic trauma in adults", section on 'Role of needle/finger chest decompression' and "Thoracostomy tubes and catheters: Placement techniques and complications".)

●Other pulmonary barotrauma – Other forms of pulmonary barotrauma can occur during air travel including pneumomediastinum, systemic air embolism, and bulla expansion with hemorrhage. Limited descriptions regarding their risk, presentation, and management exist. Presumably, they are rare and the mechanism is similar to that described for pneumothorax. (See 'Other barotrauma during air travel' above.)